[Cashtab] [pub key fetch from chronik p2] Deprecate bch-api

Summary:
T2730

Depends on D12180

Remove bch-api calls and debug logging. Add more specific error handling for edge case failures.

Test Plan:
npm start
Send an encrypted msg to an address with outgoing txs, no issues
Send an encrypted msg to an address without outgoing txs, fails with expected error msg

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Differential Revision: https://reviews.bitcoinabc.org/D12209